Didn’t always want to go into 3 gear, so will not go over 45mpg..is it a speed cancer or is it in the transmission
I think it is the speed sensor located in the transmission or the wiring harness for the speed sensor. But to be certain some testing would be recommended. Try the sensor first if it is affordable to do so. Then move on to testing the wiring, etc.
2002 Olds Bravada transmission speed sensor wiring diagram
